A hybrid vehicle may launch (e.g., accelerate from a stop) via power provided by an engine, a motor, or a combination of the motor and the engine. It may be desirable to supply a known amount of motor and/or engine torque during vehicle launch to vehicle wheels so that the vehicle accelerates at a desired rate. However, variations in manufacturing and clutch wear may make it difficult to know how much torque is being provided to vehicle wheels. Consequently, a vehicle may not behave as is desired during vehicle launch.
The inventors herein have recognized the above-mentioned issues and have developed a method for controlling a transmission launch clutch, comprising: adjusting a dual layshaft transmission clutch position during a vehicle stop and while vehicle brakes are applied; and adjusting a clutch actuator position during a vehicle launch responsive to an amount of torque transferred through the dual layshaft transmission clutch during adjusting the dual layshaft transmission clutch position during the vehicle stop.
By adjusting clutch operation during conditions when a vehicle is stopped, it may be possible to determine a clutch transfer function that may be applied during vehicle launch conditions. For example, an amount of torque transferred through a transmission clutch may be determined based on current supplied to a driveline integrated starter generator (DISG) while the DISG is operating in a speed control mode and while an application force applied by a clutch actuator is adjusted. The amount of torque transferred versus the clutch position or clutch application force may be stored as a clutch transfer function in memory. The clutch transfer function may then be applied during a vehicle launch to provide a desired torque from the engine to vehicle wheels.
The present description may provide several advantages. For example, the approach may reduce the possibility of reduced or increased vehicle acceleration relative to desired vehicle acceleration. Additionally, the approach may reduce clutch wear. Further, the approach may improve vehicle launch smoothness.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.